Dissociation of Ca2+ from sarcoplasmic reticulum Ca2+-ATPase and changes in fluorescence of optically selected Trp residues. Effects of KCl and NaCl and implications for substeps in Ca2+ dissociation.
AuthorsChampeil P, Henao F, de Foresta B
JournalBiochemistry
PubMed ID9315879
'Sequential dissociation of the two Ca2+ ions bound to non-phosphorylated sarcoplasmic reticulum Ca2+-ATPase was triggered by addition, in a stopped-flow experiment, of quin2, which acted both as a high-affinity chelator and as a Ca2+-sensitive fluorescent probe. The kinetics of Ca2+ dissociation were deduced from the observed changes in quin2 fluorescence ... More
Kinetic control of the dissociation pathway of calmodulin-peptide complexes.
AuthorsBrown SE, Martin SR, Bayley PM
JournalJ Biol Chem
PubMed ID9013581
'The mechanism of dissociation reactions induced by calcium chelators has been studied for complexes of Drosophila calmodulin with target peptides, including four derived from the skeletal muscle myosin light chain kinase target sequence. Reactions were monitored by fluorescence stopped-flow techniques using a variety of intrinsic probes and the indicator Quin2. ... More
The role of cytosolic free Ca2+ and protein kinase C in acetylcholine-induced insulin release in the clonal beta-cell line, HIT-T15.
AuthorsHughes SJ, Chalk JG, Ashcroft SJ
JournalBiochem J
PubMed ID2183793
'We examined the contribution of signal-transduction pathways to acetylcholine-induced insulin release in the clonal beta-cell line HIT-T15. To assess the importance of changes in cytosolic free Ca2+ [( Ca2+]i), we studied time courses of the effects of glucose and acetylcholine on [Ca2+]i and insulin release in quin 2-loaded HIT cells. ... More
Calbindin-D28K, a 1 alpha,25-dihydroxyvitamin D3-induced calcium-binding protein, binds five or six Ca2+ ions with high affinity.
AuthorsLeathers VL, Linse S, Forsén S, Norman AW
JournalJ Biol Chem
PubMed ID2351677
'Calbindin-D28K is a 1 alpha,25-dihydroxyvitamin D3-dependent protein that belongs to the superfamily of high affinity calcium-binding proteins which includes parvalbumin, calmodulin, and troponin C. All of these proteins bind Ca2+ ligands by an alpha-helix-loop-alpha-helix domain that is termed an EF-hand. Calbindin-D28K has been reported previously to have four high affinity ... More
Voltage-dependent activation and inactivation of calcium channels in PC12 cells. Correlation with neurotransmitter release.
AuthorsDi Virgilio F, Milani D, Leon A, Meldolesi J, Pozzan T
JournalJ Biol Chem
PubMed ID2439506
'The existence and mechanisms of inactivation of voltage-gated Ca2+ channels are important, but still debatable, physiological problems. By using the Ca2+ indicators quin2 and fura-2, we demonstrate that in PC12 cells voltage-gated Ca2+ channels undergo inactivation dependent on both voltage and [Ca2+]i. Inactivation, however, is never complete and a small ... More
Calcium indicator dye Quin2 inhibits hydrogen peroxide-induced DNA strand break formation via chelation of iron.
AuthorsBurkitt MJ, Milne L, Tsang SY, Tam SC
JournalArch Biochem Biophys
PubMed ID8203894
'Exposure of HeLa cells to H2O2 at 4 degrees C caused DNA strand breakage which was prevented by the metal chelator 1,10-phenanthroline, but not by neocuproine. This is believed to indicate the participation of iron, rather than copper, in the formation of reactive hydroxyl radicals (.OH) from H2O2. The calcium ... More
Calcium signalling in non-excitable cells: notes on oscillations and store refilling.
AuthorsRink TJ, Hallam TJ
JournalCell Calcium
PubMed ID2670242
'Technical advances in studying cellular calcium concentrations, and discoveries about many aspects of signal transduction have transformed this field of biology since this Journal was launched a decade ago. At that time monitoring of the key variable, cytoplasmic free Ca2+ concentration [Ca2+]i, was possible with aequorin or arsenazo ill mainly ... More
Verapamil and cyclosporin A sensitize human kidney tumor cells to vincristine in absence of membrane P-glycoprotein and without apparent changes in the cytoplasmic free Ca2+ concentration.
AuthorsNygren P, Larsson R
JournalBiosci Rep
PubMed ID1972632
'Vincristine (Vcr) dose dependently inhibited growth of the kidney adenocarcinoma cell line ACHN during 4 days of culture. Verapamil (Ver) at 10 microM and cyclosporin A (CsA) at 1 microgram/ml had no effect on cell growth but significantly potentiated the action of Vcr, despite the absence of the multidrug resistance ... More
Extracellular nucleotides mediate Ca2+ fluxes in J774 macrophages by two distinct mechanisms.
AuthorsGreenberg S, Di Virgilio F, Steinberg TH, Silverstein SC
JournalJ Biol Chem
PubMed ID3392016
'We have studied the effects of extracellular nucleotides on the cytosolic free calcium concentration [( Ca2+]i) in J774 macrophages using quin2 and indo-1 as indicator dyes. Micromolar quantities of ATP induced a biphasic increase in [Ca2+]i: a rapid and transient increase (peak I) which was due to mobilization of Ca2+ ... More
Cytosolic ionized calcium concentration in isolated chondrocytes from each zone of the growth plate.
AuthorsIannotti JP, Brighton CT
JournalJ Orthop Res
PubMed ID2738769
'In isolated chondrocytes from the growth plate, there is an increase in both the cytosolic ionized calcium concentration and in total cell calcium content as the cells approach the mineralization front. The reserve zone chondrocytes have a cytosolic ionized calcium concentration, [Ca2+]i, of 124 +/- 23 nM and a total ... More
Characterization of indo-1 and quin-2 as spectroscopic probes for Zn2(+)-protein interactions.
AuthorsJefferson JR, Hunt JB, Ginsburg A
JournalAnal Biochem
PubMed ID2116741
'1-[2-Amino-5-(6-carboxyindol-2-yl)phenoxyl]-2-(2''- amino-5''-methylphenoxy)ethane-N,N,N'',N''-tetraacetic acid (indo-1) and 2-[2-(bis(carboxymethyl)amino-5-methylphenoxy) methyl]-6- methyl-8-[bis-(carboxymethyl)amino]quinoline (quin-2) are sensitive, spectral indicators for Zn2+. Additions of subsaturating Zn2+ to 10-80 microM indo-1 or quin-2 at pH 7.0 produce uv difference spectra with isosbestic wavelengths at 342 and 282 nm or at 342, 317, and 252 nm, respectively. Formation of ... More
Electrostatic contributions to the binding of Ca2+ in calbindin D9k.
AuthorsLinse S, Johansson C, Brodin P, Grundström T, Drakenberg T, Forsén S
JournalBiochemistry
PubMed ID1988017
'A set of accurate experimental data is provided for Ca2+ ion binding to calbindin D9k, a protein in the calmodulin superfamily of intracellular regulatory proteins. The study comprises both the role of protein surface charges and the effects of added electrolyte. The two macroscopic Ca2(+)-binding constants K1 and K2 are ... More
Effect of secretagogues on cytosolic free Ca2+ and insulin release at different extracellular Ca2+ concentrations in the hamster clonal beta-cell line HIT-T15.
AuthorsHughes SJ, Chalk JG, Ashcroft SJ
JournalMol Cell Endocrinol
PubMed ID2673890
'We have examined the relationship between extracellular Ca2+, cytosolic free Ca2+ and insulin release in the clonal beta-cell line HIT-T15. Glucose-stimulated insulin release was dependent on the extracellular Ca2+ concentration in a dose-related manner; the threshold medium Ca2+ concentration for glucose-stimulated insulin release was 0.5 mM. Both forskolin and 12-O-tetradecanoylphorbol ... More
IgE receptor-activated calcium permeability pathway in rat basophilic leukemia cells: measurement of the unidirectional influx of calcium using quin2-buffered cells.
AuthorsFewtrell C, Sherman E
JournalBiochemistry
PubMed ID2962633
'The intracellular calcium indicator and buffer quin2 has been used to generate a large calcium buffering capacity in the cytoplasm of rat basophilic leukemia cells. Above 3 mM intracellular quin2, there is no further increase in the initial rate of antigen-induced 45Ca uptake, suggesting that 45Ca buffering by quin2 is ... More
Calcium-dependent nitric oxide production is involved in arsenite-induced micronuclei.
AuthorsGurr JR, Liu F, Lynn S, Jan KY
JournalMutat Res
PubMed ID9729339
'Arsenic, a human carcinogen is known to induce sister-chromatid exchanges, chromosome aberrations and micronuclei (MN), but its mechanisms remain unknown. Recently, independent studies have suggested that intracellular calcium and reactive oxygen species are involved in arsenite-induced MN, and nitric oxide (NO) is involved in arsenite-induced poly(ADP-ribosylation). The aim of this ... More
Solitary calcium spike dependent on calmodulin and plasma membrane Ca2+ pump.
AuthorsFoder B, Scharff O
JournalCell Calcium
PubMed ID1334811
'Resealed human red cell ghosts were loaded with Fura-2, ATP, Mg2+, and either calmodulin (CaM) or, to prevent CaM activation of the Ca2+ pump, a synthetic peptide that antagonized endogenous CaM (an analogue of the CaM binding domain of protein kinase II, referred to as ''antiCaM''). The ghosts reduced the ... More
Imaging of inositol 1,4,5-trisphosphate-induced Ca2+ fluxes in single permeabilized hepatocytes. Demonstration of both quantal and nonquantal patterns of Ca2+ release.
AuthorsRenard-Rooney DC, Hajnóczky G, Seitz MB, Schneider TG, Thomas AP
JournalJ Biol Chem
PubMed ID8226887
'The subcellular organization and function of inositol 1,4,5-trisphosphate (InsP3)-sensitive Ca2+ stores has been investigated in permeabilized hepatocytes using fluorescent probe techniques that monitor InsP3 action at the level of the Ca2+ storage organelles. Chlortetracycline fluorescence was used to follow alterations in luminal Ca2+, and InsP3-activated Mn2+ quench of compartmentalized fura-2 ... More
Quantitation of bovine sperm cytoplasmic calcium with Quin-2 and Fura-2: evidence that external calcium does not have direct access to the sperm cytoplasm.
AuthorsVijayaraghavan S, Hoskins D
JournalCell Calcium
PubMed ID2776189
'Internal calcium levels of sperm loaded with Quin-2 in the absence or presence of exogenous calcium were 63 +/- 5 and 189 +/- 19 nM, respectively. These values were similar to those determined by Fura-2. Surprisingly, however, dye loaded sperm depleted of internal calcium did not take up calcium from ... More
Gonadotropin-releasing hormone-induced rise in cytosolic free Ca2+ levels: mobilization of cellular and extracellular Ca2+ pools and relationship to gonadotropin secretion.
AuthorsNaor Z, Capponi AM, Rossier MF, Ayalon D, Limor R
JournalMol Endocrinol
PubMed ID2458525
'Addition of GnRH to pituitary gonadotrophs preloaded with Quin 2 resulted in a rapid (approximately 8 s) mobilization of an ionomycin-sensitive intracellular Ca2+ pool. A second component of Ca2+ entry via voltage dependent channels contributed about 45% of the peak cytosolic free Ca2+ concentration ([Ca2+]i). Thereafter, influx of Ca2+ via ... More
Effects of subtilisin cleavage of monomeric actin on its nucleotide binding.
AuthorsOoi A, Mihashi K
JournalJ Biochem (Tokyo)
PubMed ID9010757
'The kinetics of ATP exchange on subtilisin-cleaved G-actin was investigated by measuring the fluorescence of 1,N6-ethenoadenosine 5''-triphosphate. The apparent dissociation rate of ATP (k-ATP) was 2.8-fold larger than that of intact G-actin in the presence of 300 microM free Ca2+. Analysis of the dependence of k-ATP on free Ca2+ showed ... More
Stopped-flow kinetics of the interaction of the fluorescent calcium indicator Quin 2 with calcium ions.
AuthorsQuast U, Labhardt AM, Doyle VM
JournalBiochem Biophys Res Commun
PubMed ID6487303
'The kinetics of the Quin 2-Ca2+ interaction have been studied using stopped-flow fluorimetry. Mixing the Quin 2-Ca2+ complex with a large excess of EGTA, EDTA or MgCl2 resulted in first order dissociation kinetics. The observed dissociation rate increased slightly with increasing EGTA concentration yielding a limiting value of 83 +/- ... More
Parathyroid hormone promotes the disassembly of cytoskeletal actin and myosin in cultured osteoblastic cells: mediation by cyclic AMP.
AuthorsEgan JJ, Gronowicz G, Rodan GA
JournalJ Cell Biochem
PubMed ID1848561
'Parathyroid hormone (PTH) alters the shape of osteoblastic cells both in vivo and in vitro. In this study, we examined the effect of PTH on cytoskeletal actin and myosin, estimated by polyacrylamide gel electrophoresis of Triton X-100 (1%) nonextractable proteins. After 2-5 minutes, PTH caused a rapid and transient decrease ... More
Ca2+ and phorbol ester activation of protein kinase C at intracellular Ca2+ concentrations and the effect of TMB-8.
AuthorsChristiansen NO, Larsen CS, Juhl H
JournalBiochim Biophys Acta
PubMed ID3011108
'A calcium-activated, phospholipid-dependent protein kinase (protein kinase C) was purified to near homogeneity from human polymorphonuclear leukocytes and shown to be identical to bovine protein kinase C. The Ca2+ activation of the enzyme was studied and the Ca2+ concentrations required to activate the enzyme were compared to free cytosolic Ca2+ ... More
Measurement of the matrix free Ca2+ concentration in heart mitochondria by entrapped fura-2 and quin2.
AuthorsLukács GL, Kapus A
JournalBiochem J
PubMed ID3435469
'A method was developed to monitor continuously the matrix free Ca2+ concentration ([Ca2+]m) of heart mitochondria by use of the fluorescent Ca2+ indicators, fura-2 and quin2. The acetoxymethyl esters of fura-2 and quin2 were accumulated in and hydrolysed by isolated mitochondria. An increase of the mitochondrial Ca content from 0.3 ... More
Hormone secretagogues increase cytosolic calcium by increasing cAMP in corticotropin-secreting cells.
AuthorsLuini A, Lewis D, Guild S, Corda D, Axelrod J
JournalProc Natl Acad Sci U S A
PubMed ID2415978
'Corticotropin (ACTH)-releasing factor, vasoactive intestinal peptide, and catecholamines--hormones that stimulate ACTH secretion and cAMP generation--increased cytosolic calcium in AtT-20 cells. The increase in intracellular calcium is presumably a consequence of the stimulated cAMP synthesis, since forskolin, an activator of the catalytic unit of adenylate cyclase, and the cAMP analog 8-bromoadenosine ... More
Do submaximal InsP3 concentrations only induce the partial discharge of permeabilized hepatocyte calcium pools because of the concomitant reduction of intraluminal Ca2+ concentration?
AuthorsCombettes L, Claret M, Champeil P
JournalFEBS Lett
PubMed ID1577167
'In several types of cells whose cytoplasmic Ca2+ is regulated by inositol phosphate derivatives, low concentrations of InsP3 added to permeabilized cell suspensions induce the rapid discharge of part of the InsPs-sensitive Ca2+ pool instead of slow monophasic release of Ca2+ from the entire pool. As a tentative explanation for ... More
Calcium transients during mitosis: observations in flux.
AuthorsHepler PK
JournalJ Cell Biol
PubMed ID2687283
Intracellular measurements of ion activities.
AuthorsTsien RY
JournalAnnu Rev Biophys Bioeng
PubMed ID6347046
Practical aspects of measuring [Ca2+] with fluorescent indicators.
AuthorsKao JP
JournalMethods Cell Biol
PubMed ID8201975
Measurement of cytosolic free Ca2+ with quin2.
AuthorsTsien R, Pozzan T
JournalMethods Enzymol
PubMed ID2747529
Receptor-mediated Ca2+ entry: diversity of function and mechanism.
AuthorsHallam TJ, Rink TJ
JournalTrends Pharmacol Sci
PubMed ID2556820
Bromo-A23187: a nonfluorescent calcium ionophore for use with fluorescent probes.
AuthorsDeber CM, Tom-Kun J, Mack E, Grinstein S
JournalAnal Biochem
PubMed ID3927770
4-Bromo-A23187, a halogenated analog of the widely studied divalent cation ionophore A23187, is a nonfluorescent Ca2+ ionophore suitable for use in the calibration of cytoplasmic free Ca2+ by fluorescent probes. Br-A23187 is shown to saturate Ca2+ sites in quin-2-loaded rat thymic lymphocytes in a manner essentially identical to ionomycin. ... More
Determination of calcium ions tightly bound to proteins.
AuthorsNitta K, Watanabe A
JournalJ Chromatogr
PubMed ID1800522
A rapid and sensitive procedure is described for the determination of calcium ions tightly bound to proteins using high-performance gel filtration chromatography, followed by the destabilization of the protein conformation and fluorimetric analysis with Quin-2. With this method, contaminating, unbound calcium can be eliminated simultaneously and one can determine the ... More
Cytosolic free calcium levels increase with age in rat brain synaptosomes.
AuthorsMartinez A, Vitórica J, Satrústegui J
JournalNeurosci Lett
PubMed ID3386880
Calcium homeostasis in synaptosomes is altered during ageing. The cytosolic free calcium concentration, [Ca2+]i was determined in synaptosomes and crude synaptosomal fractions from 3- and 24-month-old rats with the fluorescent indicator quin-2. The [Ca2+]i were around two times higher in 24-month-old rats than in adults, both under resting conditions and ... More
A new method of determining intracellular free Ca2+ concentration using Quin2-fluorescence.
AuthorsMiyoshi N, Hara K, Kimura S, Nakanishi K, Fukuda M
JournalPhotochem Photobiol
PubMed ID2062883
We determined intracellular free Ca2+ concentration by fluorescence spectroscopy and the time-resolved measurements of 2-[(2-amino-5-methylphenoxy) methyl]-6-methoxy-8-aminoquinoline-N,N,N',N'-tetraacetic acid, tetrapotassium salt (Quin2) incorporated in suspended mouse leukemia L1210 cells. The paper reports the following two points. (1) Various fluorescence spectrum patterns in cell suspensions dissolved with Quin2 acetoxy methylester were compared with ... More
Free calcium in isolated chick embryo heart cells measured using quin2 and fura-2.
AuthorsJacob R, Murphy E, Lieberman M
JournalAm J Physiol
PubMed ID3618767
Cytosolic free calcium (Cai) was measured using quin2 and fura-2 in isolated chick embryo heart cells. Account was taken of extracellular quin2 and fura-2 (which could not be entirely washed away) by adding Mn. Shortly after loading with quin2, Cai was 49 nM (n = 7) but then rose continuously ... More
Calcium transients in single adrenal chromaffin cells detected with aequorin.
The effect of 55 mM K+ and nicotine on intracellular free calcium was monitored in bovine adrenal chromaffin cells microinjected with aequorin. In contrast to results with quin 2, which suggested that stimulation of chromaffin cells resulted in sustained rises in free calcium, aequorin measurements showed that 55 mM K+ ... More
Dynamic fluorescence measurements of two-state systems: applications to calcium-chelating probes.
AuthorsHirshfield KM, Toptygin D, Packard BS, Brand L
JournalAnal Biochem
PubMed ID8470792
A fluorescence technique for characterizing ligand binding is evaluated. This technique uses the combination of steady-state and time-resolved methods to recover molar concentrations and overcomes errors inherent in the use of either method alone. The technique is applicable to time-resolved measurements made either with time-domain or frequency-domain instrumentation. A straightforward ... More
A new device for monitoring concentrations of intracellular Ca2+ in CNS preparations and its application to the frog's spinal cord.
AuthorsKudo Y, Takeda K, Hicks TP, Ogura A, Kawasaki Y
JournalJ Neurosci Methods
PubMed ID2586154
For monitoring the changes in intracellular concentrations of Ca2+ in vertebrate CNS neurones in situ, we devised an assembly of two quartz-made optic fibres enclosed in a glass capillary. Esterified fluorescent Ca2+ indicator (quin2/AM) was injected into the motoneuronal pool of the frog's spinal cord, and about 60 min later, ... More
Calbindin D(9k): a protein optimized for calcium binding at neutral pH.
AuthorsKesvatera T, Jönsson B, Telling A, Tõugu V, Vija H, Thulin E, Linse S
JournalBiochemistry
PubMed ID11735416
The binding of calcium ions by EF-hand proteins depends strongly on the electrostatic interactions between Ca(2+) ions and negatively charged residues of these proteins. We have investigated the pH dependence of the binding of Ca(2+) ions by calbindin D(9k). This protein offers a unique possibility for interpretation of such data ... More
Nucleotide binding to actin. Cation dependence of nucleotide dissociation and exchange rates.
AuthorsKinosian HJ, Selden LA, Estes JE, Gershman LC
JournalJ Biol Chem
PubMed ID8473312
We have reinvestigated nucleotide binding to actin in order to resolve conflicts regarding the mechanism of nucleotide dissociation and exchange. We present evidence that supports a mechanism for nucleotide binding to actin in which the tightly bound divalent cation (Ca2+ or Mg2+) directly interacts with the bound nucleotide. The dissociation ... More
Effect of age on K+-induced cytosolic Ca2+ changes in rat cortical synaptosomes.
AuthorsGiovannelli L, Pepeu G
JournalJ Neurochem
PubMed ID2746228
45Ca2+ uptake and cytosolic Ca2+ concentrations [( Ca2+]i) were measured in synaptosomes prepared from the cerebral cortex of 3-, 16-, and 24-month-old male Charles River Wistar rats. Electron-microscopic examination demonstrated no morphological differences between the synaptosomes prepared from 3- and 24-month-old rats. The fast phase of Ca2+ uptake was reduced ... More
Interactions between inositol trisphosphate receptors and fluorescent Ca2+ indicators.
AuthorsMorris SA, Correa V, Cardy TJ, O'Beirne G, Taylor CW
JournalCell Calcium
PubMed ID10326680
Fura-2 and BAPTA were previously shown to be competitive antagonists of inositol trisphosphate (InsP3) receptors, but for practical reasons the analyses were performed at pH 8.3. We recently developed a scintillation proximity assay (SPA) for pure cerebellar InsP3 receptors which allows low affinity interactions to be characterized and is readily ... More
Prolonged high intracellular free calcium concentrations induced by ATP are not immediately cytotoxic in isolated rat hepatocytes. Changes in biochemical parameters implicated in cell toxicity.
AuthorsNagelkerke JF, Dogterom P, De Bont HJ, Mulder GJ
JournalBiochem J
PubMed ID2597107
Isolated rat hepatocytes were incubated with ATP to induce high intracellular free Ca2+ concentrations as determined with the Quin-2 method. Immediately after addition of ATP, the intracellular concentration of Ca2+ rose from 200 nM to more than 2.5 microM. It stayed at this value during the first 1/2 h; the ... More
Relation of cytosolic calcium to the microbicidal activation of blood monocytes by recombinant gamma interferon.
AuthorsKemmerich B, Small GJ, Pennington JE
JournalJ Infect Dis
PubMed ID3021865
Oxygen metabolism and calcium ion (Ca++) handling in blood monocytes were greatly affected by treatment with recombinant gamma interferon (rIFN-gamma). Incubating the monocytes with rIFN-gamma resulted in increased basal production of superoxide anion, as well as a significantly enhanced respiratory burst in response to concanavalin A (Con A). A concomitant ... More
Modulation of Ca2+ exchange with the Ca(2+)-specific regulatory sites of troponin C.
Calcium (Ca2+) binding to the N-terminal Ca(2+)-specific sites on troponin C (TnC) regulate the contraction-relaxation cycle of skeletal muscle. A mutant TnC (F29W) and dansylaziridine-labeled TnC undergo large fluorescence increases when Ca2+ binds to their Ca(2+)-specific sites (half-maximal at pCa 5.8). Calmidazolium and the additional mutation of Met-82 to Gln ... More
Aldosterone influences free intracellular calcium in human mononuclear leukocytes in vitro.
AuthorsWehling M, Käsmayr J, Theisen K
JournalCell Calcium
PubMed ID2285925
Mineralocorticoid receptors have been detected in human mononuclear leukocytes (HML) and a physiological effector mechanism was demonstrated subsequently by which aldosterone is able to prevent the loss of intracellular sodium, potassium and cell water during incubation in an aldosterone-free medium. In the present paper, free intracellular calcium, [Ca2+]i, was measured ... More
Partition of the organochlorine insecticide lindane into the human sperm surface induces membrane depolarization and Ca2+ influx.
AuthorsSilvestroni L, Fiorini R, Palleschi S
JournalBiochem J
PubMed ID9032455
The effects of the insecticide lindane (the gamma-isomer of 1,2,3,4,5,6-hexachlorocyclohexane) on membrane potential, cytosolic free Ca2+ concentration ([Ca2+]i) and surface biophysical properties were studied in human spermatozoa. The insecticide induces rapid, transient and reproducible membrane depolarization and opening of voltage-dependent Ca2+ channels leading to an increase in [Ca2+]i. In contrast ... More
Is the augmentation of K+-evoked intrasynaptosomal Ca2+ concentration due to the influx of Ca2+ in rat brain synaptosomes?
AuthorsOkada M, Mine K, Iwasaki K, Fujiwara M
JournalJ Neurochem
PubMed ID2723639
Intraterminal free Ca2+ concentration modulates the subsequent release of neurotransmitters. Depolarization of synaptosomes with 29 mM K+ augments cytosolic free Ca2+ concentration, which is triphasic, the peak times being at 10, 60, and 180 s. We examined the characteristics of each elevation of cytosolic free Ca2+ concentration in rat brain ... More
Intracellular Ca2+ pools in PC12 cells. Three intracellular pools are distinguished by their turnover and mechanisms of Ca2+ accumulation, storage, and release.
AuthorsFasolato C, Zottini M, Clementi E, Zacchetti D, Meldolesi J, Pozzan T
JournalJ Biol Chem
PubMed ID1939077
Three, non-cytosolic Ca2+ pools were characterized in intact PC12 cells. The first pool, sensitive to both inositol 1,4,5-trisphosphate and caffeine (Zacchetti, D., Clementi, E., Fasolato, C., Zottini, M., Grohovaz, F., Fumagalli, G., Pozzan, T., and Meldolesi, J. (1991) J. Biol. Chem. 266, 20152-20158) accounts for approximately equal to 200 microM ... More
The fourth EF-hand of calmodulin and its helix-loop-helix components: impact on calcium binding and enzyme activation.
AuthorsGeorge SE, Su Z, Fan D, Wang S, Johnson JD
JournalBiochemistry
PubMed ID8679587
CaM (4 cTnC) is a calmodulin--cardiac troponin C chimeric protein containing the first, second, and third calcium-binding EF-hands of calmodulin (CaM) and the fourth EF-hand of cardiac troponin C (cTnC) [George, S.E., Su, Z., Fan, D., & Means, A.R. (1993) J. Biol. Chem. 268, 25213-25220]. CaM (4 cTnC) showed 2-fold-enhanced ... More
New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures.
AuthorsTsien RY
JournalBiochemistry
PubMed ID6770893
A new family of high-affinity buffers and optical indicators for Ca2+ is rationally designed and synthesized. The parent compound is 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a relative of the well-known chelator EGTA [ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] in which methylene links between oxygen and nitrogen are replaced by benzene rings. BAPTA and ... More
Properties of tri- and tetracarboxylate Ca2+ indicators in frog skeletal muscle fibers.
AuthorsZhao M, Hollingworth S, Baylor SM
JournalBiophys J
PubMed ID8789107
Recently a number of lower-affinity fluorescent Ca2+ indicators have become available with principal absorbance bands at visible wavelengths. This article evaluates these indicators, as well as two shorter wavelength indicators, mag-fura-5 and mag-indo-1, for their suitability as rapid Ca2+ indicators in frog skeletal muscle fibers. With three lower-affinity tricarboxylate indicators ... More
Effects of wheat germ agglutinin on the cellular content of filamentous actin in Intestine 407 cells.
AuthorsSjölander A, Magnusson KE
JournalEur J Cell Biol
PubMed ID3229418
Increasing experimental evidence suggests that gluten contains a toxic factor that may cause ultrastructural changes in the small intestine which mimic those found in patients with celiac disease. In addition, it has recently been proposed that the toxic factor of gluten is a protein very similar, if not identical, to ... More
Interaction of neutrophil elastase with hydrophobic polyanionic chelators.
AuthorsTyagi SC, Simon SR
JournalBiochem Cell Biol
PubMed ID1793563
The polyanionic calcium chelators, ethylenediamine-tetraacetic acid (EDTA), ethylene-bis-(oxyethylenenitrilo)-tetraacetic acid (EGTA), [bis-(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA), 1-[2-amino-5-(6-carboxyindol-2-yl) phenoxyl]-2-(2'-amino-5'-methylphenoxy)ethane-N,N,N1, N1-tetraacetic acid (INDO-1), 1-[2-(5-carboxyoxazol-2yl)-6-phenoxyl]-2-(2'-amino-5'- methylphenoxy)ethane-N,N,N',N'-tetraacetic acid (FURA-2), and 2-([2-bis-(carboxymethyl)-amino-5-methylphenoxy]-methyl(-6-methyl-8- bis-(bis-(carboxymethyl)-aminoquinoline (QUIN-2), are all inhibitors of amidolytic activity of human neutrophil elastase (HNE). With MeOSuc-Ala-Ala-Pro-Val-pNA as substrate, these chelators all display mixed partial competitive and partial ... More
Measurement of cytoplasmic free Ca2+ concentration in cultured muscle cells by aequorin and quin 2.
AuthorsJames-Kracke MR
JournalAm J Physiol
PubMed ID3094376
Ca2+ has been proposed to regulate expression of the gene for the Ca2+ pump of the sarcoplasmic reticulum in developing chicken myoblasts (A. N. Martonosi, L. Dux, R. L. Terjung, and D. Roufa. Ann. NY Acad. Sci. 402: 485-514, 1982. In the present study, intracellular free Ca2+ ([Ca2+]i) was measured ... More
Oxidized glutathione causes sensitization of calcium release to inositol 1,4,5-trisphosphate in permeabilized hepatocytes.
AuthorsRenard DC, Seitz MB, Thomas AP
JournalBiochem J
PubMed ID1599435
The effects of GSSG on Ca2+ mobilization by Ins(1,4,5)P3 were studied in permeabilized rat hepatocytes. Incubation with GSSG (2 mM) increased the sensitivity to Ins(1,4,5)P3 for Ca2+ release, with no effect on the size of the Ca2+ pool that could be released with maximal concentrations of Ins(1,4,5)P3. GSSG decreased the ... More
Oscillatory cytosolic calcium waves independent of stimulated inositol 1,4,5-trisphosphate formation in hepatocytes.
AuthorsRooney TA, Renard DC, Sass EJ, Thomas AP
JournalJ Biol Chem
PubMed ID2061312
The mechanisms underlying agonist-induced oscillations in intracellular free calcium ion concentration ([Ca2+]i) in hepatocytes were investigated by utilizing tert-butyl hydroperoxide (TBHP) as a tool to perturb hepatocyte Ca2+ homeostasis independent of receptor activation. In permeabilized hepatocytes, TBHP inhibited Ca2+ uptake into the inositol 1,4,5-trisphosphate (InsP3)-sensitive Ca2+ pool and increased the ... More
ANF inhibits vasopressin-induced Ca2+ mobilization and contraction in glomerular mesangial cells.
It has been suggested that atrial natriuretic factor (ANF) may increase glomerular filtration rate (GFR) via alteration of the glomerular ultrafiltration area, which is at least in part regulated by the contractile state of mesangial cells. The present study therefore investigated the effect of ANF (atriopeptin III) on arginine vasopressin ... More
Regulation of epidermal growth factor-stimulated formation of inositol phosphates in A-431 cells by calcium and protein kinase C.
AuthorsWahl M, Carpenter G
JournalJ Biol Chem
PubMed ID3259577
Epidermal growth factor (EGF) treatment of A-431 cells induces a biphasic increase in the levels of inositol phosphates. The growth factor produces an initial, rapid increase in the level of inositol 1,4,5-trisphosphate (Ins-1,4,5-P3) due to hydrolysis of phosphatidyl-inositol-4,5-bisphosphate (Wahl, M., Sweatt, J. D., and Carpenter, G. (1987) Biochem. Biophys. Res. ... More
Hydrophobic core substitutions in calbindin D9k: effects on Ca2+ binding and dissociation.
AuthorsKragelund BB, Jönsson M, Bifulco G, Chazin WJ, Nilsson H, Finn BE, Linse S
JournalBiochemistry
PubMed ID9636034
Hydrophobic core residues have a marked influence on the Ca2+-binding properties of calbindin D9k, even though there are no direct contacts between these residues and the bound Ca2+ ions. Eleven different mutants with substitutions in the hydrophobic core were produced, and their equilibrium Ca2+-binding constants measured from Ca2+ titrations in ... More
Designing calcium-sensitizing mutations in the regulatory domain of cardiac troponin C.
AuthorsTikunova SB, Davis JP
JournalJ Biol Chem
PubMed ID15205455
Cardiac troponin C belongs to the EF-hand superfamily of calcium-binding proteins and plays an essential role in the regulation of muscle contraction and relaxation. To follow calcium binding and exchange with the regulatory N-terminal domain (N-domain) of human cardiac troponin C, we substituted Phe at position 27 with Trp, making ... More
Intracellular calcium recordings from isolated cells of the mammalian central nervous system.
AuthorsMorris ME, MacDonald JF, Friedlich JJ, Szekelyhidi I
JournalCan J Physiol Pharmacol
PubMed ID3621053
Measurements made with two different techniques of intracellular calcium levels from small isolated cells of the mammalian central nervous system are described and compared. Recordings in cultured mouse embryo spinal cord and dorsal root ganglion neurons, made with double-barrelled borosilicate Ca2+-selective microelectrodes yielded a mean Ca2+ level of 2.3 (SE ... More
Control of cytosolic free calcium by intracellular organelles in bovine adrenal glomerulosa cells. Effects of sodium and inositol 1,4,5-trisphosphate.
The regulation of cytosolic free Ca2+ concentration ([Ca2+]c) by intracellular organelles was studied in permeabilized bovine adrenal glomerulosa cells. Two compartments, with distinct characteristics, were able to pump Ca2+. A first pool, sensitive to ruthenium red and presumably mitochondrial, required respiratory chain substrates to maintain [Ca2+]c around 700 nM. Ca2+ ... More
Calcium signaling in human platelets.
AuthorsRink TJ, Sage SO
JournalAnnu Rev Physiol
PubMed ID2158766
The past three years have seen significant advances in our knowledge and understanding of Ca2+ mobilization in platelets. Some of the data has shown that systems demonstrated in other cell types operate in platelets, while in certain respects platelet studies have provided the lead with new insights and approaches. An ... More
Chelation of intracellular calcium prevents stimulation of glucose transport by insulin and insulinomimetic agents in the adipocyte. Evidence for a common mechanism.
AuthorsPershadsingh HA, Gale RD, McDonald JM
JournalEndocrinology
PubMed ID3311718
Vanadate, concanavalin A (Con A), H2O2, and the phorbol ester, 12-O-tetradecanoyl phorbol 13-acetate (TPA), seemingly unrelated compounds, have effects on cellular metabolism similar to those of insulin. The mechanism(s) by which these diverse compounds act and their relevance to insulin action remain unclear. The hypothesis that increased intracellular calcium ([Ca2+]i) ... More
Unfolding energetics of G-alpha-actin: a discrete intermediate can be re-folded to the native state by CCT.
AuthorsAltschuler GM, Klug DR, Willison KR
JournalJ Mol Biol
PubMed ID16171816
Nascent actin requires interactions with the highly conserved and essential eukaryotic chaperonin-containing TCP-1 (CCT) for its correct folding to the native state in vivo. Biochemical and structural analysis of the interaction between actin and CCT has been studied extensively but the underlying energetics and kinetics of the CCT-dependent actin folding ... More
Alpha 1-adrenergic stimulation and cytoplasmic free calcium concentration in cultured renal proximal tubular cells: evidence for compartmentalization of quin-2 and fura-2.
AuthorsGoligorsky MS, Hruska KA, Loftus DJ, Elson EL
JournalJ Cell Physiol
PubMed ID3755726
This study was designed to examine the role of changes in cytoplasmic free calcium concentration ([Ca2+]i) during the response to alpha 1-adrenergic agonists in cultured renal proximal tubular cells. Experiments were carried out on primary cultures of canine proximal tubular cells grown in defined culture medium on a solid support, ... More
The high affinity calcium-binding sites in the epidermal growth factor module region of vitamin K-dependent protein S.
AuthorsStenberg Y, Linse S, Drakenberg T, Stenflo J
JournalJ Biol Chem
PubMed ID9287334
Vitamin K-dependent protein S, a cofactor of the anticoagulant enzyme-activated protein C, has four epidermal growth factor (EGF)-like modules, all of which have one partially hydroxylated Asp (EGF 1; beta-hydroxyaspartic acid) or Asn (EGF 2, 3, and 4; beta-hydroxyasparagine) residue. The three C-terminal modules have a typical Ca2+ binding sequence ... More
Cardiac troponin T isoforms affect the Ca(2+) sensitivity of force development in the presence of slow skeletal troponin I: insights into the role of troponin T isoforms in the fetal heart.
AuthorsGomes AV, Venkatraman G, Davis JP, Tikunova SB, Engel P, Solaro RJ, Potter JD
JournalJ Biol Chem
PubMed ID15358779
In this study we investigated the physiological role of the cardiac troponin T (cTnT) isoforms in the presence of human slow skeletal troponin I (ssTnI). ssTnI is the main troponin I isoform in the fetal human heart. In reconstituted fibers containing the cTnT isoforms in the presence of ssTnI, cTnT1-containing ... More
Adenosine triphosphate, bradykinin, and thyrotropin-releasing hormone regulate the intracellular Ca2+ concentration and the 45Ca2+ efflux of human thyrocytes in primary culture.
AuthorsRaspé E, Andry G, Dumont JE
JournalJ Cell Physiol
PubMed ID2506191
The hormonal stimulation of phospholipase C and the consequent activation of the Ca2+-phosphatidylinositol cascade in eukaryotic cells is associated with modifications of the [Ca2+]i (intracellular Ca2+ concentration) which modulates cellular functions. In this study, these modifications were investigated in primary cultures of human thyroid cells. The mean apparent basal [Ca2+]i ... More
Characterizing the response of calcium signal transducers to generated calcium transients.
AuthorsDavis JP, Tikunova SB, Walsh MP, Johnson JD
JournalBiochemistry
PubMed ID10194340
Cellular Ca2+ transients and Ca2+-binding proteins regulate physiological phenomena as diverse as muscle contraction, neurosecretion, and cell division. When Ca2+ is rapidly mixed with slow Ca2+ chelators, EGTA, or Mg2+/EDTA, artificial Ca2+ transients (ACTs) of varying duration (0.1-50 ms half-widths (hws)) and amplitude can be generated. We have exposed several ... More
Kinetic studies of calcium binding to regulatory complexes from skeletal muscle.
AuthorsRosenfeld SS, Taylor EW
JournalJ Biol Chem
PubMed ID3965450
The kinetic mechanism of the binding and release of calcium by troponin and by the complexes troponin: tropomyosin, troponin:tropomyosin:actin, and troponin (TN)-tropomyosin (TM)-actin:myosin subfraction 1 (SF-1) was investigated using troponin labeled on the TN-I subunit with the fluorophore 4-(N-iodoac etoxyethyl-N-methyl)-7-nitrobenz-2-oxa-1,3-diazole. The apparent association constant is five to 10 times smaller ... More
Free cytoplasmic calcium concentration and the mitogenic stimulation of lymphocytes.
AuthorsHesketh TR, Smith GA, Moore JP, Taylor MV, Metcalfe JC
JournalJ Biol Chem
PubMed ID6601105
The effects of the lectins concanavalin A, succinylated concanavalin A, and wheat germ agglutinin on the free cytoplasmic Ca2+ concentration in mouse thymocytes were measured using the fluorescent Ca2+ indicator "quin 2" (Tsien, R. Y. (1980) Biochemistry 19, 2396-2404) and compared with the metabolic and mitogenic effects of the lectins ... More
The complex of actin and deoxyribonuclease I as a model system to study the interactions of nucleotides, cations and cytochalasin D with monomeric actin.
AuthorsPolzar B, Nowak E, Goody RS, Mannherz HG
JournalEur J Biochem
PubMed ID2500340
The stoichiometric actin--DNase-I complex was used to study the actin--nucleotide and actin--divalent-cation interactions and its ATPase activity in the presence of MgCl2 and cytochalasin D. Treatment of actin--DNase-I complex with 1 mM EDTA results in almost complete restoration of its otherwise inhibited DNase I activity, although the complex does not ... More
Catalytic significance of the specificity of divalent cations as KS* and kcat* cofactors for secreted phospholipase A2.
Calcium is required for the substrate binding and for the chemical step of the interfacial catalytic turnover cycle of pancreatic phospholipase A2 (PLA2), but not for the binding of the enzyme to the interface. The role of calcium and other divalent cations (C) is analyzed for the effect on the ... More